Process of burning ceramic ware.



No. 810,044. PATENTED JAN. 16, 1906.

. B. E. ELDRED. PROCESS OF BURNING CERAMIC WARE.

APPLICATION FILED IEB.21. 1905.

2 SHEETS-BHEBT 1.

WITNESSES.

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ATTORN EYS No. 810,044. PATENTED JAN. 16, 1906. B. E. ELDRED.

PROCESS OF BURNING CERAMIC WARE.

APPLICATION FILED FEB. 21. 1905.

2 SHEETS-SHEET 2 UNITED STATES PATENT OFFICE.

BYRON E. ELDRED, OF BRONXVILLE, NEW YORK, ASSIGNOR TO COMBUSTION UTILITIES COMPANY, OF NEW YORK, N. Y., A (JOR- PORATION OF NEW YORK.

Specification of Letters Patent.

Patented Jan. 16, 1906.

Application filed eb uary 21, 1905. Serial No. 246,656.

To all whom it may concern.-

Be it known that I, BYRON E. ELDRED, acitizen of the United States, residing at Bronxville, county of Westchester, State of New York,have invented certain new and useful Improvements in Processes of Burning Ceramic VYare, of which the following specification and accompanying drawings disclose as an illustration one embodiment thereof which I now re- F gard as the best out of the various forms in which the principles of my invention may be applied.

This invention relates to the art of burning ceramic ware, including bricks, tile, pottery, &c.

In my Patent No. 692,257 is disclosed a slow-burning voluminous flame produced by .the use of products of combustion in the draftcurrent supplied to the fire under conditions afiording perfect control of the temperature, volume, and duration of combustion and affording a comparatively cool fuel-bed under accelerated draft. This flame constitutes an artificial force which can be applied to the ceramic art with considerable resultant saving in fuel, improvement in product, and decrease in the period of burning over present methods. In the practice of my present invention I find it necessary to first prepare the ware for the operation of this flame by a process of preliminary drying or water-smoking, which brings the contents of the kiln into a heat-retaining condition very desirable for sustaining the ignition and completing the combustion of a heating agent of this peculiar character the combustion whereof is much slower and more outspread than that of any other flame which I have observed. The water-smoking or preliminary dryingv step requires a comparatively low temperature and may be performed either by products of combustion from a burning-kiln, or by air heated by the contents of a burned kiln, or by both agencies combined. For the performance of this step, as well as for carrying out my present process as a whole, I have devised certain novel apparatus, which, however, is not claimed herein. When the ware has lost most or all of its mechanically and chemically combined water,l apply the long flame, inflated by a predetermined proportion of products of combustion derived from one or more burning-kilns and passed through the fires. The

. presence of the diluent results in cooling the fire-boxes and carrying the flame much farther into the heart of the kiln than heretofore, there being, in fact, a considerable body of flame in contact with the articles under treatment even with fires at some distance away. Such a heating by local combustion rather than by hot air or the gaseous emanations of a fire is found to be highly eflicient and to result in a material shortening of the burning process. It also aflords a more even heat and avoids overburning of the articles nearest the fires and slack burning at remote points. Owing to the nature of the ware and its manner of treatment in stationary batches which acquire a steadily-increasing temperature up to the termination of the process, I find it desirable and advantageous to vary the composition of the draft-current in accordance with the condition of the ware. In the early stages of burning the proportion of neutral gases to air or oxygen is kept small and the flame comparatively short. It may be made so short at first (though longer than the ordinary flame) by a gentle forced draft and a small proportion of diluent as not to reach the ware in this early stage of burning, in which case some advantage is realized by bringing the combustion nearer to the ware and yet retaining a cool fuel-bed. As the ware acquires a higher temperature capable of sustaining ignition at a greater distance from the seat of initial combustion the pro portion is increased and the flame lengthened. The draft may be strongly accelerated without any danger of excessive temperature in the fire-boxes or in the kiln, and the acceleration may increase as the high-temperature zone extends. Thus it becomes possible to bu rn bricks and similar ware with an economy in fuel consumption impossible of attainment with the ordinary process of combustion restricted to a natural or only moderately-accelerated draft of fixed composition. Furthermore, by simply varying the composition of the draft-current of a flaming fuel-bed I am enabled to produce a flame of oxidizing, neutral, or reducing character at will and to alternate its quality in order to reduce or avoid discolorations in the ware. I prefer to heat the air with which the products of combustion in the draft-current are mixed by carrying it through a burned kiln, as this allows a larger proportion of such products to be employed. The carbonic acid of the products acts both endothermically and sensibly as a cooler and produces carbonic oxid in the fuel-bed. Hence the employment of preheated air results in a larger evolution of combustible gases and a longer flame.

1n the accompanying drawings, Figure 1 represents a plan or diagrammatic view of a group of brick-kilns constructed to carry out the invention and arranged on the progressive plan. Fig. 2 represents a section of one of the kilns.

The same reference characters indicate the same parts in both figures.

1,0 is the body of the kiln. For simplicity of illustration the several kilns are shown each with only a single fire-box 11.

Each has a lateral flue or tunnel 12 under the perforated floor 120,connecting with a longitudinal trunkflue 121, leading to the stack 122. I have also shown downdraft-kilns, although the invention applies to updraft and horizontal-draft kilns as well.

13 is the grate of the fire-box, 14 the ashpit, and 15 the fire-chamber, whereby the'flrebox is equipped to burn coal or other solid fuel, although I do not restrict myself as to the kind of fuel.

16 is the main chamber, in which the bricks 17 or other ceramic ware are placed, and 18 is a partition extending from the fire-box nearly to the roof of the kiln and forming one side of a refractory-walled flue 19, whereby the flame and products of combustion are caused to enter the contents of the kiln from above and pass downwardly to the out-draft passage 12. In the early-stages of burning with the diluent when the flame is comparatively short this refractory-walled flue has an important function as a heat-retainer, serving to maintain the ignition of the flame and complete its combustion when the ware itself is not capable of fully performing that function.

Products of combustion are drawn from the flue 12 of a burning-kiln by a fan-blower 20 and introduced to the ash-pit 14 in company with a predetermined supply of air forced in by another fan 28. The draft is accelerated by the fans, and the presence of products of combustion causes an elongation and inflation of the flame, whereby the latter burns at an increased distance from the firebox and finally develops a large portion of its heat energy directly in contact with the bricks 17. This makes any given weight of fuel more efficient in burning the bricks, besides burning them more evenly and quickly. The flame in its initial stage passes through the flue 19 and is thereby subjected to an igniting influence, which-tends to maintain combustion and perpetuate it within the materials in the body of the kiln. The character of this flame is in marked contrast with the short hot flame produced by an ordinary coal fire and is more like that of a wood fire, although much cheaper to produce in most localities. Forced draft does not have the ordinary elfect of increasing the intensity of combustion; but, on the contrary, the firebox is comparatively cool.

Fig. 1 shows a unit consisting of six kilns, (numbered 1 to 6, inclusive.)

21 is a pipe for products of combustion, having a suction connection by branches 22 with the lateral tunnels 12 of the several kilns and leading to the suction side of the fan 20, from which a delivery-pipe 24 connects by branches 25 with the ash-pits of the several fire-boxes.

26 is a hot-air pipe having suction connection by branches 27 with the several tunnels 12 and leading to the suction side of the airfan 28, from which a delivery-pipe 29 communicates by branches 30 with the several ash-pits. The delivery branches 25 and 30 are siamesed before each fire-box to mix the components of the draft-currents. Suitable valves or dampers 31 in. the difierent branches enable the fans to draw from the outlets of any one or more of the kilns anddeliver to the fireboxes of any one or more of said kilns. The exit-tunnels 12 also have dampers 34 for connecting them with or shutting them off from the trunk-flue 121, and the latter has a stackdamper 35. The pipes 24 29 may be continued at 32 33 to the driers, (if such are employed,) wherein any residue of heat in the air or products of combustion delivered by the fans which is not needed in the kilns may be employed in partially drying the bricks before they come to the kilns.

The above arrangement enables the various stages of brick-burning and similar operations to be carried on simultaneously and with economical interrelation. For example, kilns Nos. 1 and 6 may be burning while kiln No. 2 is cooling, No. 3 is emptying, No. 4 filling, and No. 5 water-smoking. A portion of the products of combustion drawn by the fan 20 from kilns 1 and 6 is returned to the ash-pits of these kilns to elongate the flames from the fires. The remaining products of combustion are passed through kiln No. 5 and their waste heat made useful in performing the initial drying or water-smoking step. Cold air is drawn through kiln No. 2 by the fan 28 (by way of charging-door 280 or fire-box) and the stored heat of the com pletely-burned contents of said kiln is yielded up to the air. A portion-of this hot air may be passed through kiln No. 5 to assist in the water-smoking, drying, or steaming step, or the whole of it may be so passed instead of or supplementary to the products of combustion. I prefer also to introduce a portion of this hot air into the ashpits of the burning-kilns 1 and 6 to promote the combustion of the fuel and increase the pro-portion of neutral gases which may be employed. Cold air, if necessary, may be taken in at the inlet 340 on the suction side of fan 20 if the supply of hot air is absent or insuflicient; but this will not be so eflicient as the hot air, and therefore it is generally desirable to have at least one kiln cooling while one or more others are burning. WVhcre there is considerable free oxygen in the burningkiln through leakage or otherwise, the proportion of air added to the draft-current for the fires may be diminished. By means of the valves or dampers provided for the purpose the proportions of air and diluent are regulated to give a flame of the desired length, temperature, and chemical composition. These factors may also be regulated by varying the speed of the fans. In the early stages of burning following water-smoking it is desirable to have a smaller proportion of products of combustion in the drafts of the fire-boxes, so as to make a shorter flame, not subjected to a great extent while in a state of incomplete combustion to the low temperature of the ware. As the contents of the kiln grow hotter the proportion of diluent is increased and the flame elongated. If alternations of oxidizing and reducing flame are desired, they may be produced by varying the proportions of air and diluent, an excess of diluent giving a reducing-flame rich in carbonic oxid, while an excess of air gives an oxidizing-flame.

The construction of the conduits and connections of the kilns here shown is somewhat diagrammatic, and it will be understood that the same idea may be embodied in different constructional forms, such as brickwork conduits, &c., while the kilns themselves may have a plurality of fire-boxes or seats of combustion, and these may be differently located, without departing from the spirit of the invention.

I am aware that various arrangements have been heretofore proposed whereby the waste gases and kiln-heated air have been utilized for drying or water-smoking the ware and increasing the intensity of combustion, mainly with the idea of deriving further heat from the gases of the fire after these have burned the ware and making effective the stored heat of the ware; but my process differs in its objects from these in being a novel method of producing and applying a heating agent to the burning of ceramic ware both for individual kilns and groups or plural units thereof.

Whatl claim as new, and desire to secure by Letters Patent, is

1. The process of burning ceramic ware which consists in subjecting a penetrable mass of said ware to a voluminous slow-burning flame produced by'passing through a bed of solid fuel an artificially-accelerated draft-current containing free oxygen and diluent neutral products of combustion in predetermined proportions, and increasing the proportion of the diluent as the high-temperature zone of the ware extends.

2. The process of burning ceramic ware which consists in subjecting theware to a voluminous slow-burning flame produced with a dilute air-draft, and varying the composition of said draft in accordance with the temperature attained by the Ware.

3. The process ofburning ceramic ware which consists in causing aflame of artificiallyretarded combustion to penetrate a mass of the ware under forced draft, and elongating the flame by a predetermined variation in its composition as the burning progresses.

4. The process of burning ceramic ware which consists in subjecting the ware to a voluminous slow-burning flame produced with an artificially-strengthened air-draft containing products of combustion in predetermined proportion, and increasing the force of said draft as the high-temperature zone extends.

5. The process of burning ceramic ware which consists in projecting a flame from a fuel-bed with an artificially-forced draft-current containing products of combustion in sufficient amount to suppress the natural intensity of combustion, causing said flame to penetrate the ware, and increasing the proportion of said products in the draft-current as the temperature of the ware increases.

6. The process of burning ceramic ware which consists in projecting a flame from a fuel-bed with an artiflcially-forced draft-current containing products of combustion in sufflcient amount to suppress the natural intensity of combustion, causing said flame to pene trate the Ware, and increasing the force of the draft-current as the zone of high temperature extends.

7. The process of burning ceramic ware which consists in projecting from a fuel-bed into a penetrable mass of the ware a flame produced with an artificially-strengthened draftcurrent containing products of combustion in suflicient amount to retard the combustion of andinflate said flame, and regulating the composition of the flame with reference to the condition'ofthe ware.

8. The process of burning ceramic ware which consists in producing a voluminous slow-burning flame with a predetermined proportion of products of combustion in the draftcurrent supplied to the flre, applying said flame under artificially-strengthened draft to a stationary mass of ceramic ware, and maintaining it in operation with increasing flame volume from the time the ware loses its Water and reaches an ignition-sustaining condition until it is completely burned.

9. The process of burning ceramic ware which consists in projecting from a fuel-bed into a mass of the ware, a voluminous slowburning flame produced with products of combustion and free oxygen in predetermined proportion in the draft-current, and alternately increasing and decreasing the proportion of products to produce alternations of reducing and oxidizing quality in the flame.

10. The process of burning ceramic ware IIO which consists in driving off the water from the green ware with a low-temperature heating agent, and then when the ware has reached a condition capable of sustaining ignition, subjecting it to a voluminous slow-burning flame produced with a predetermined proportion of products of combustion in the draft-current supplied to the fire, increasing the volume of said flame as burning proceeds.

11. The process of burning ceramic ware which consists in subjecting the ware in a kilnchamber to a voluminous flame of artificiallyretarded combustion produced with products of combustion and air in the draft-currentsupplied to the fire, and preheating the air by the heat from burned ware in a difiierent kiln-chamber.

12. The process of treating ceramic ware which consists in subjecting it to the heat of a flaming fuel-bed through which is passed a predetermined proportion of products of combustion, and subjecting the flame to the igniting influence of a refractory heat-retainer in advance of the ware until the major part of its combustion is completed.

13. The process of burning ceramic ware which consists in diluting and dilating firegases with products of combustion and with air in such relative proportions as to give a tardily-burning mixture, passing such mixture through a hot-walled ignition-flue, thoroughly admixing the gases and inaugurating combustion therein, and continuing the combustion in immediate proximity to the ware to be burned.

14. The process of burning ceramic ware which consists in burning a penetrable mass of such ware in a kiln with a gradually-elongating flame.

In witness whereof I have hereunto set my hand this 4th day of January, 1905;

BYRON E. ELDRED.

l/Vitnesses:

OWEN WARD, E0131. 0. LEWIS. 

